1. An information system's characteristics that permit an adversary to probe, attack, or maintain presence in the information system.
2. The set of ways in which an adversary can enter a system and potentially cause damage.
Source: Explore Terms: A Glossary of Common Cybersecurity Terminology, National Initiative for Cybersecurity Careers and Studies (NICCS), https://niccs.us-cert.gov/about-niccs/glossary; The Cyber Glossary, National Security Archive, George Washington University, https://nsarchive.gwu.edu/news/cyber-vault/2018-09-19/cyber-glossary
3. Attack vector: Mechanism or method used by an attacker to gain access to a target’s computer system and/or deliver an effect.
Source: U.S. Cyberspace Solarium Commission, March 2020, https://subscriber.politicopro.com/f/?id=00000170-c638-d8f7-a7f1-f63b33510000